1. Field of the Invention
This invention relates to an eye direction detecting apparatus for finding an eye direction or a gaze point of a user's eye in a finder system.
2. Description of the Prior Art
An eye direction detecting apparatus is known in which the apparatus makes incident a light bundle to a photographer's eye, and detects the reflection light of the eye in the shape of video signals, and then calculates a revolving angle of the eye based upon the video signals.
However, the above-mentioned eye direction detecting apparatus generally uses some optical units in common with the light emitting system and the light receiving system. The detected signal includes noise signals as the ghost signals generated from the common optical units.
FIG. 8 shows data representing ghost signals generated from the above-mentioned conventional apparatus' optical system. In FIG. 8, an abscissa shows a bit number of the CCD line sensor, and an ordinate shows an amount of light as the ghost signals.
Such ghost signals deform the video signals for detection of the eye direction. Examples of the shapes of deformed video signals are shown in FIG. 9, FIG. 10 and FIG. 11.
FIG. 9 shows a case in which a photographer's eye direction is in the center of a finder. In this case, it seems that there is little disturbance in processing of the data. But actually, ghost signals influences the accuracy, of the eye direction measurement to some degree.
FIG. 10 shows a case in which the photographer's eye direction is in the right direction of the finder. In this case, the left side of the output video signals' shape is lifted a greater deal. When the photographer's eye direction is in the left direction of the finder, as shown in FIG. 11, the right side of the output video signals' shape is lifted a great deal. These deformations of the video signals influences much the accuracy of the eye direction measurement.
FIG. 12 illustrates an enlarged view of an eye to explain a relationship between a first Purkinje image and the center of an eye.